A great place to start Disorder information source Rated and Reviewed Sleep Links Entrance to all monitored Sleep Forums Search all of Sleepnet.com


Tech Forum
Posting


Archived Tech Forums viewing only.

Re: Arnold Chiari Malformation and Sleep Disordered Breathing


Posted by Zoey on October 29, 1999 at 06:21:26:

In Reply to: Arnold Chiari Malformation and Sleep Disordered Breathing posted by Simon Kemp on November 04, 1998 at 22:51:29:

January 1, 1999

Division of Neurosurgery Begins New Study of the Chiari I Malformation

The increasing use of MRI to diagnose neurologic problems is leading to a greater recognition of the Chiari I malformation. Still, many patients have symptoms years before the problem is identified. The Division of Neurosurgery at MU has begun a prospective study of the Chiari I malformation that focuses on characterizing the wide variety of symptoms and defining the short and long term outcome following treatment. Information about symptoms, signs, MRI features, surgical treatment, and outcome at one month, 3 months, one year, 5 year and 10 years following treatment will be recorded and analyzed.

The study is for patients that have not had previous Chiari surgery. We will track detailed pre-operative evaluations and compare them to the short and long term outcomes following surgery. This should lead to a better understanding of Chiari I management in patients not previously treated for the disorder.


Summary of the Chiari I Malformation
Definition
The Chiari I malformation is a congenital anomaly of unknown etiology that consists of a small posterior fossa and herniation of the cerebella tonsils into upper cervical canal. The Chiari I malformation may be associated with a cavity in the spinal cord (syringomyelia).

Clinical Presentation
Patients with the Chiari I malformation present with one or more signs and symptoms of brainstem, cranial nerve, cerebellar or spinal cord dysfunction including:

headache (especially cough headache)
neck pain
disordered eye movements
trigeminal dysesthesia
sensorineural hearing loss
tinnitus
dizziness
dysphagia
sleep apnea
nystagmus
dysarthria
ataxia
dysethesias/numbness
sensory loss
weakness, greater in the upper than lower extremities
Diagnosis
Magnetic resonance imaging (MRI) is the test of choice in diagnosing the Chiari I malformation. The Chiari I malformation is present when the tonsils are herniated 5 mm or more below the foramen magnum. If the cerebellar tonsils are herniated from 3-5 mm, the Chiari malformation is diagnosed if there are associated changes such as cervicomedullary kinking, elongation of the 4th ventricle, or syringomyelia.

Treatment
When symptoms of the Chiari I malformation develop, a posterior fossa and upper cervical decompression needs to be considered. This provides more room around the lower brainstem and promotes improved neurologic functioning. In many patients with syringomyelia, the cyst will often decrease in size following posterior fossa decompression. In others, cyst shunting may be required.

Outcome
Outcome following treatment varies, but is generally good. Early diagnosis and treatment may lead to better outcome. The MU Chiari trial hopes to answer this and other questions about the Chiari I malformation.
*****************************************************************************************************************************************

What are Chiari malformations?
Chiari malformations occur in the region where the brain and spinal
cord join. The lowerportions of the brain (cerebellar and/or
brainstem) are located lower than normal, penetrating out of the skull
or protruding into the spinal canal.
Chiari malformations were first described in the 1890's by Professor
Chiari, a German pathologist. He assigned a grade to the malformations
beginning with Type I, the mildest form, classification today. Chiari
malformations are also known by the followi ng medical terms:
herniation of the cerebellar tonsils, cerebellar ectopia, hindbrain
herniation, and Arnold-Chiari malformations, with Arnold-Chiari
malformations being specific to type II malformations. Scientists and
physicians further define Chiari malformations by the exact millimeter
of brain stem that extends into the neck.
Chiari type I malformations are a result of the smallest degree of
herniation and are not associated with spina bifida. Chiari type II
malformations are almost exclusively associated with a type of spina
bifida known as a myelomeningocele, an opening of the spine and spinal
cord on the lower back. Chiari type III and IV malformations are very rare.
What other disorders can occur with Chiari malformations?
Chiari malformations can occur with other conditions. Some are:
* hydrocephalus (excessive fluid in the brain)
* spina bifida (opening of the spine usually associated with an
abnormality of the spinal cord)
* syringomyelia (excessive fluid in the spinal cord, leading to a
cavity detectable by MRI).
* other conditions, including some inherited conditions like
achondroplasia (a type of dwarfism), Hajdu-Cheney syndrome,
Albright hereditary osteodystrophy (pseudohypoparathyroidism), or
other rarer syndromes.
Many individuals with Chiari malformations do not have any other
associated medical problems. How common are Chiari malformations?
There are no data describing the incidence of Chiari malformations.
However, malformations of the cervico-medullary junction, the
connection between the brain and spine, are present in approximately 1
percent of live newborns. The most common cervico-medullary junction
malformations are Chiari malformations.
What are the symptoms of a Chiari malformation? Symptoms:
* Some patients with Chiari malformations are without symptoms. When
symptoms are present, headache and neck pain are the most common
complaint.
The affected regions of the brain are the lower brainstem and
cerebellum. The lower brainstem controls breathing, swallowing,
balance, the vocal cords, eye movements, and sensation and
movement of the arms and legs. The cerebellum's most important
function is to coordinate body movements. Symptoms of a Chiari
malformation are often vague and many times diagnosis of a Chiari
malformation is delayed.
Some individuals with Chiari malformations report vertigo
(dizziness), headaches caused by coughing, weakness in their arms,
a burning-like pain in the arms, severe curvature of the spine and
other symptoms.
The severity of symptoms is often associated with the degree of
pressure on this portion of the brain. Therefore an individual
with a "small Chiari malformation" may have very mild symptoms or
no symptoms at all. Some individuals with Chiari malformation
never develop symptoms. What causes Chiari malformations?
Scientists do not know the cause of Chiari malformations. Still, there
are several hypotheses. One theory suggests that the base of the skull
is too small in some individuals and this forces the cerebellar region
lower than it should be. Another theory suggests that the growth of
the cerebellar region is thrown off and overgrowth occurs resulting in
the cerebellar region of the brain being compressed lower than it
should be. Research studies are ongoing to learn how Chiari
malformations occur.
How is syringomyelia associated with Chiari malformations?
Syringomyelia (sear-IN-go-my-EEL-ya) is a disorder where abnormal
collection of fluid occurs the spine. This collection of fluid,
composed of cerebral spinal fluid (CSF), is referred to as a "syrinx"
or a "cyst." Syringomyelia can be occur as a res ult of a car accident
or other trauma. Syringomyelia can also occur with Chiari
malformations or spinal tumors. The symptoms and signs of this
disorder are often vague and may include weakness, fatigue, stiffness,
or loss of ability to feel hot or cold.
Syringomyelia can be diagnosed with a magnetic resonance imaging (MRI)
study. Are Chiari malformations inherited?
There are several families reported in medical literature in which
more than one family member has a Chiari malformation. However, no
research study has ever been done to prove or disprove whether Chiari
malformations are inherited. If more than one person in your family
has a Chiari malformation or a spinal cord problem, please contact
Medical Genetics's toll free telephone number (800) 283-4316.
Participation in the study involves answering questions about
family and medical history, allowing Medical Genetics researchers to
review medical records to confirm the diagnosis of Chiari
malformation, and in some instances PROVIDING A BLOOD SAMPLE to the
researchers.
*******************************************************************************************************************************
Introduction Arnold-Chiari Malformation (ACM) is a malformation of the cervico-medullaryjunction characterized by displacement of the cerebellar tonsils, the brainstemand the fourth ventricle into the upper cervical canal. [13] The clinicalpresentation of this anomaly is largely dependent upon age at onset, associatedpathology, and the presence of hydromyelia. Considerable controversy exists within the Neurology literature concerningpathogenesis, signs and symptoms, diagnosis, and successful treatment. Thisarticle will examine these issues and discuss the management of a patient withthis syndrome. The first description of Arnold-Chiari malformation was offered byJohn Cleland in 1883. [4] Cleland described pathological findings in nineinfants which consisted of elongation of the brainstem and extension of thecerebellum into the cervical canal. Apparently unware of Cleland's work,Chiari reported two types of hind brain anomalies in 1891. Type I had thecerebellar tonsils below the foramen magnum while Type II ha
d the medullaand fourth ventricle descended as well as was the associated with amyelomeningocele. [10] Three years after Chiari's report, Arnold describedthe case of a newborn infant with multiple anomalies. Among these wereherniation of the fourth ventricle and parts of the cerebellum with themedulla described as normal. [4] This description was consistent withChiari 1. The differentiation of the Chiari 1 and 2 malformation was alteredin 1907 when two of Arnold's students, Schwalbe and Gredig, added Arnold'sname to the Type II malformation and coined the term "Arnold-Chiari malformation" [3] These authors were the first to describe the "kink" atthe cervico-medullary junction in the Type II anomaly.They further distinguished the cerebellar malformation as Arnold'smalformation and the medullar malformation as Chiari's deformity. Discrepancies in the nomenclature still exist today. Some authorsprefer to reserve the term Arnold-Chiari malformation for the Type IIanomaly, while others prefer the classification of
the Chiari Type I andChiari Type II. For the purposes of this article, the author distinguishesbetween Arnold-Chiari malformation Type I (ACM I) and Arnold-Chiarimalformation Type II (ACM II). [(S4.2)-----------------------------------------------------------------------] Anatomy and Physiology To facilitate a better understanding of the pathophysiology of this complexdisease, it is necessary to examine the anatomy and physiology of the posteriorfossa (Figure 1). The posterior fossa contains the brainstem, cerebellum, andthe fourth ventricle. Located inferior to the diencephalon and superior to thepons, midbrain is the most rostral brain structure. The midbrain is composedprimarily of a large bundle of fibers called the cerebral peduncles. With thesefibers lies the major motor pathway, the corticospinal tract. Traversing themidbrain is the cerebral aqueduct which connects third and fourth ventricles.The midbrain also contains the nuclei of the oculomotor(III) and trochlear(IV)cranial nerves. Inferior to the
midbrain is the pons which functions as the conductionpathway for motor and sensory fibers from the cerebrum to the spinal cord.[1]On the basilateral surface of the pons are the middle cerebellar peduncleswhich provide extensive connections between the cerebral cortex and thecerebellum. The nuclei of the trigeminal(V), abducens(VI), facial(VII)and vestibulocochlear(VIII) cranial nerves are located in the pons whichmakes it an important reflex center for cranial nerve function. Also locatedwithin the pons are the reticular formation and the pneumotaxic centers. Inferior to the pons is the most caudal brainstem structure, the medulla.Like the pons, the medulla acts as a conduction pathway for motor and sensoryfibers. [1] The nuclei of the glossopharyngeal(IX), vagus(X), spinal accessory(XI) and hypoglossal(XII) cranial nerves are contained in the medulla. Along with the protective functions of these lower cranial nerves, the medulla contains groups of neurons that influence respirations, vomiting, hiccuping,and
vasomotor responses. The medulla extends through the foramen magnum togradually become the spinal cord. [6] The cerebellum overlies the posterior aspect of the pons and medullaand extends laterally under the tentorium to fill the greater portion of theposterior fossa. [3] It consists of three lobes: anterior, posterior, andflocculonodular. The cerebellum is responsible for muscle synergy throughoutthe body. It coordinates the action of muscle groups and times theircontractions so that the movements are performed smoothly and accurately. [6]It is also responsible for the control of the muscle tone and the maintenanceof equilibrium. The fourth ventricle is a rhomboid-shaped cavity posterior to thepons and medulla that extends from the central canal of the upper cervicalspinal cord to the cerebral aqueduct of the midbrain. [5] CerebrospinalFluid (CSF) flows from the lateral ventricles through the foramen of MONROto the third ventricle. From the third ventricle, it travels through thecerebral aqueduct into the f
ourth ventricle. From the fourth ventricle, CSF can exit through one of three foramina. Fluid may exit through either oneof two foramina of LUSCHKA, which are located at the lateral portions ofthe fourth ventricle, and empty into the PONTINE CISTERN, or it may passthrough the FORAMEN OF MAGENDIE into the caudal extent of the fourth ventricleand enter the CISTERNA MAGNA. [5] From these cisterns, the CSF enters thesubarachnoid space and flows over the cerebral hemispheres and spinal cord.It then progresses toward arachnoid villi and is reabsorbed into the venouscirculation. [5,7] [(S4.3)----------------------------------------------------------
**********************************************************************************************************************************************
Pathophysiology The most striking feature of Arnold Chiari Malformation is the caudaldisplacement of the cerebellar tonsils and the fourth ventricle into theforamen magnum or upper cervical canal. [12] Compression of the tonsils,which are often asymmetrical, may give them a flattened, malformed appearance.Necrosis of the tonsillar tips and gliotic cysts with them may develop. Themedulla is often kinked and has a nodular appearance. [12] Hydrocephalus maydevelop from obstruction of the CSF outflow from the fourth ventricle. Thereis often a membrane over the foramen of Magendie or fibrovascular adhesionsaround the cerebellum and the brainstem at the level of the foramen magnum.[10] The downward displacement of the spinal cord may cause the cervical nerveroots to assume a rostral course rather than travel in a caudal direction. Adhesions over foramen of Magendie are often associated with Hydromyelia.Hydromyelia is a condition in which the central canal of the spinal cordcommunicates with the fourth ventricle and
is dis-tended by CSF.The distendedcavity progressively damages the cord by compression of the anterior horns andthe corticospinal and long sensory pathways. Some of the features of Arnold-Chiari malformation with hydromyelia are illustrated in Figure 2. [(S4.4)-----------------------------------------------------------------------] Pathogenesis Since its first description by Cleland in 1883, several theories have beenproposed in an attempt to explain the etiology of Arnold-Chiari Malformation.An early view was that the anomaly results from a tethered spinal cord thatpulls posterior fossa structures downward. In the presence of a myelomeningocele, traction exerted on the cordmechanically pulls against the brainstem and cerebellum, forcing the cervicalnerve roots to travel in rostral direction. [1] Although this theory mayprovide an explanation for the hindbrain anomaly in the presence of spinabifida, it does not explain the mechanism in the absence of such lesions. [3]This view has since been discredited. Cle
land attributed the Malformation toa primary dysgenesis of the brainstem. [3] Peach elaborated on this theory byproposing that the dysgenesis would prevent the normal formation of thepontine flexure, thus elongating the brainstem into the cervical canal. [10]Calling this "arrested development," [3,7] Peach noted the relative incidenceof the associated anomalies of the ACM II and argued that these are indicativeof the same mechanism. [3] A third view that the abnormalities in the neural cleft result in anabnormally small posterior fossa. As the cerebellum tries to fill the small bony compartment, it develops in an abnormally low position which results in herniation into the cervical canal. [10] Another theory is that the anomaly results from local overgrowth of thebrainstem and generalized overgrowth of the cerebrum. [3] The excessivecerebral volume would force the tentorium down, thereby reducing the posteriorfossa. Caudal displacement of cerebellum and brainstem would then result.[10] In 1965, Gardner put fo
rth the hydrodynamic hypothesis which suggests thatthe condition results from alterations in CSF dynamics at the craniospinaljunction. [2] Gardner proposes that failure of the primitive rhombic roof tobe permeable during fetal development results in an obstruction of the foramenof Magendie. The closed neural tube becomes dilated and the ventricles enlarge.This hydrocephalus forces the tentorium and the hindbrains to migrate in acaudal direction. [3,10,11] Several theories specifically address the pathogenesis of hydromyelia.Williams suggests that defective intracranial drainage partially obstructsthe flow of CSF from the cranium into the distensible spinal subarachnoidspaces. [2] The central canal is then forcefully distended because ofabnormalities of venous pressure. Fluid within the syrinx travel down thecentral canal from the floor of the fourth ventricle. [2,10] Gardner explains the development of hydromyelia by the hydrodynamichypothesis. He proposes that the slowly progressive cystic dilation of thecor
d results from arterial pulsations of CSF which are transmitted to the cervical cord because of impaired outflow from the fourth ventricle. [2,13] Several authors have questioned Gardner's hydrodynamic theory. Theseauthors argue that the relatively rare incidence of hydrocephalus in ACM-1indicates that hydrocephalus is not the sole causative factor. [2,10,14,18]Nevertheless, Gardner's theory has contributed significantly to a betterunderstanding of this complex disease and provided insight into its surgicalmanagement; however, an universally accepted concept is still lacking. [(S4.5)-----------------------------------------------------------------------] Classification Some of the distinguishing features of Chiari's classification ofArnold-Chiari Malformation are illustrated in table 1. However a review ofcases in the literature suggests that this may be an over-simplification.Some of the classical distinctions of ACM II are found in ACM I as well.ACM II usually occurs in infancy and has a more striking prese
ntationbecause of associated anomalies and a spinal dysraphic lesion. For these reasons, it is considered first throughout the remainder of this discussion. The anomalies associated with ACM II include microgyria, forking of theaqueduct, cysts of the foramen of Magendie, abnormalities of the septum pellucidum, hemivertebrae, beaking of the tectum, hypoplasia of the falx tentorium, and thickening of the interhalamic connection. [7]Spina bifida and hydrocephalus are rarely absent. A kink in the medullaoccurs in 55 percent of the cases. The cranial nerves are elongated and thecervical nerve roots run upward toward their foramina. [1,7] In most cases,there is caudal displacement of the cerebellar tonsils, inferior vermis,medulla, and the fourth ventricle. ACM I usually occurs in adults and is rarely associated with hydrocephalusor spina bifida. In the classical description of ACM I, the hindbrain anomalyis restricted to the cerebellum and the fourth ventricle. The medullary kinkis absent; the cranial nerves are n
ot elongated; and the cervical nerve rootstravel their normal course.[1] In several series reviewed, however, descent ofthe brainstem, kinking of the medulla, and cranial nerve abnormalities arereported to accompany the disorder as well. [10,12,13] Unlike ACM II,hydromyelia is frequently associated with ACM I. [2] When hydromyelia ispresent, intense scarring over the foramen of Magendie is often seen. [12] [(S4.6)-----------------------------------------------------------------------] Clinical Presentation The clinical presentation of patients with Arnold-Chiari malformation ishighly variable. The majority of children with ACM II have an associatedmyelomeningocele. The signs and symptoms observed in these children canusually be attributed to dysplasia or hydrocephalus. More than 90 percent ofthese patients develop hydrocephalus within the first six months followingclosure of the spinal defect. [3,10] Cranial nerve palsies are commonly seen in ACM II. Particularly affectedare the lower cranial serves: the glos
sopharyngeal(IX), vagus(X), spinalaccessory(XI) and hypoglossal(XII). Degeneration of their nuclei and hypoplasiaof the vagus nerve may be exhibited by a poor suck or gag reflex or a shrillcry. Laryngeal stridor and vocal cord paralysis may predispose the child torespiratory distress. Hypotonia, weakness and spasticity in the upper extremities are frequentlyseen as a result of brainstem compression and the abnormal course of thecervical nerve roots. Exacerbation of these symptoms may progress toquadriplegia. [3] Abnormalities of the spine are often associated with ACM II. These includebony malformation of the cervical-medullary junction, platybasia, assimilationof the atlas, basilar impression of the Klippel-Feil deformity. [3] Othermanifestation of ACM II include cerebellar signs, nystagmus, and symptomsreferable to the hydrocephalus such as irritability and vomiting. [1] Patients with ACM I usually present with a combination of progressivebulbar and cerebellar signs. [12] Gait ataxia, nystagmus, diplopia,dy
sarthria, and dysphagia are indicative of these abnormalities. Downbeatnystagmus as the salient manifestation of the disorder has been reported. [8]Respiratory stridor resulting from a the sudden onset of vocal cord paralysishas been described as well. [13,14] Headache or pain in the cervical region is a common occurrence. The painmay increase with coughing or sneezing as alterations in cerebrospinal fluidpressure occur. Increased intercranial pressure or hydrocephalus are rarelyseen. When hydromyelia is associated with ACM I, myelopathy and a dissociatedsensory loss occur. [10] This is characterized by weakness and atrophy inthe upper extremities and loss of pain and temperature sensation in a cape-likedistribution around the shoulders and arms. Upper and lower motor neuron signsmay be seen in the lower extremities. These include spasticity, hyperactivereflexes, weakness, and atrophy. Dysesthesias and proprioceptive disturbancesmay also occur. In most cases, the upper extremities are affected first andthe se
nsory disturbances precede motor signs. [13] These findings arecharacteristic of a central cord syndrome. The onset is insidious and theprogression slow. [14] Scoliosis is frequently present and neurogenicarthropathies may develop in the later stage of the disease. [(S4.7)-----------------------------------------------------------------------] Diagnosis -
***********************************************************************************************************************************
NEURORADIOLOGY IN 1985: The two components of diagnostic evaluation for Arnold-Chiari malformationare the clinical examination and radiological studies. The clinicalexamination focuses not only on physical abnormalities of the motor, sensoryand reflex systems but also on patient's subjective report of pain anddysesthesia. Due to the vague nature of the symptoms and the variable course,misdiagnosis is common. Patients are frequently diagnosed with progressiveneurologic disorders: MULTIPLE SCLEROSIS (MS), AMYOTROPHIC LATERAL SCLEROSIS(ALS), MYASTHENIA GRAVIS, MUSCULAR DYSTROPHY, CERVICAL SPONDYLOSIS andCERVICAL MYELOPATHY. Other patients maybe be labeled "neurotic" because of vague complaints ofheadache and sensory abnormalities. Furthermore, not all patients have aclassical picture of deeply herniated tonsils, [10] in these patients,radiologic studies may fail to locate any pathology. Since these factorsoften obscure the correct diagnosis, an active investigational attitude isessential. The purpose of radiolog
ic techniques is to demonstrate the nature andextent of the lesion, the presence of hydromyelia or hydrocephalus, thelocation of the cerebellar tonsils, and the existence of associatedanomalies. [14] Initial radiologic a examination consists of plain x-raysof the skull and cervical spin. In the child with ACM II, this often doesnot take place until after closure of the spinal defect. Skull films inthese children demonstrate enlargement of the cranium or craniolacunia in85 percent of cases. [3] Other abnormalities which may be seen includeKlippel-Feil deformity, platybasia, basilar impression, assimilation of theatlas, scoliosis, and hemi-vertebra. Plain film abnormalities are lesscommon in ACM-1. In a restrospective study, Levy et al. recently reportedabnormalities in 36 percent of patients who had skull films and in35 percent of those patients with cervical x-rays. Other authors report alower incidence of these findings. [3,8,13,14] Positive contrast myelography using iophendylate (Pantopaque) or metrizamide
(Amipaque) will demonstrate the low position of the cerebellar tonsils and compression of the upper cervical cord. Studies in the prone position alone may fail to locate any pathology. [12,13] and studies of the spinal cord alone may be normal even in the presence of hydromyelia. It is therefore recommended that myelography be performed in both the prone andsupine positions with the attention focused at the foramen magnum.When there is an associated syrinx, a widened cervical cord may be identified.Even if the cord size is normal the diagnosis of ACM with hydromyelia isestablished if tonsillar herniation on myelography is coupled with abnormalfindings of a central cord syndrome on neurological examination. [11]This finding is unusual in ACM II. [2] Angiography of the posterior fossa may be performed to visualize thevenous system and exclude the presence of a space-occupying lesion. Althoughrarely performed on infants, the venous phase in these studies may reveallow placement of the transverse sinuses and ano
malies of the dural sinuses.[3]In the adult, angiography demonstrates displacement of the cerebellar tonsilsas defined by the low descent of the posterior cerebellar artery (PICA).[13] Conventional COMPUTERIZED AXIAL TOMOGRAPHY (CT) SCANNING is negative inmost ACM I because hydrocephalus is frequently absent, the fourth ventriclemay not appear abnormal, and the foramen magnum is not well demonstrated.[2] CT scanning is more useful in ACM II as it can distinguish betweenhydrocephalus associated with this malformation and hydrocephalus of otheretiologies. [3] Other studies include air myelography, pneumoencephalography, andventriculography. These studies have been replaced recently by theuse of delayed CT scanning after the intrathecal injection of metrizamide.This study is particularly useful in detecting the hydromyelic cavityassociated with ACM I. [9,10,13,15]. The most promising diagnostic development for the identification ofArnold-Chiari malformation and hydromyelia is the use of Nuclear MagneticResonance
(NMR/MRI). As this procedure becomes more widely used, it willprobably provide complete identification of these lesions and virtuallyreplace the need for invasive procedures.[ADDED PARAGRAPH:]Diagnosis - NEURORADIOLOGY IN SEPTEMBER 1996 (eleven years later): MRI is now the neurodiagnostic test of choice. Utilizing T1 and T2 imagesin two planes (sagittal plus axial or coronal), the brain's and spinal cord'sanatomic detail is exquisitely delineated. Hindbrain anomalies, hydrocephalus,and hydromyelic (referring to water within the spinal cord) cavities are welldemonstrated on T1 images. Intra medullary (inside) spinal cord tumors andarachnoiditis (inflammation of the coverings of the spinal cord and itsnerves) that appear indistinguishable from hydromyelia on the T1 image developabnormal signal intensity on multi-echo or T2 images. Furthermore, MRI (Magnetic Resonance Imaging) affords an accurate and veryobjective measure of spinal cord and cyst size pre and postoperativelywithout the potential risks of irradia
tion, post contrast seizure and asepticmeningitis which are present with metrizamide. In patients with bonyanomalies of the craniovertebral junction, noncontrast thin section (6 mm.)CT (Computerized Axial Tomography) scanning of the upper cervical spineforamen magnum and clivus is performed. [(S4.8)-----------------------------------------------------------------------] Treatment - NEUROSURGERY Most infants with ACM II have an associated myelomeningocele. The initialtreatment for these children is surgical repair of the dysraphic lesion.Hydrocephalus usually develops following closure of this defect, necessitatinga shunting procedure. In rare instances, symptoms of posterior fossa compression, such asrespiratory or motor dysfunction, may progress even after shunting. Inthese cases, a surgical decompressive procedure is required. The goal ofsurgery is to decompress the cerebellar tonsils and the upper cervical cord,and to restore flow of cerebrospinal fluid from the fourth ventricle.[3] Treatment of the adult
form of this condition (ACM I) presents a much greater challenge to the neurosurgeon. Most authors agree that treatment should consist of a suboccipital craniectomy and upper cervical laminectomyto decompress the malformation at the foramen magnum.[10,12,13,14] Whenhydromyelia accompanies the malformation, however, there is much lessagreement about the most effect mode of therapy.The hydrodynamic theory has formed the basis for several methods of surgicaltreatment aimed at redirecting the flow of the cerebrospinal fluid away fromthe syrinx (Figure 3). Gardner initially recommended a procedure consistingof posterior fossa decompression of the foramen magnum, opening the foramenof Magendie, and plugging the central canal at the obex with a piece ofmuscle. [10,13] Subsequent reports indicate that progress of symptoms iscommon with this procedure. Rhoton advocates a microsurgical procedure that includes suboccipitalcraniectomy and cervical laminectomy, establishing free outflow from thefourth ventricle and draini
ng the cord via a posterolateral myelotomy; inhis series of 40 patients there are no reports of progressive neurologicdeficits. [12,13]Syrinx shunting is recommended by some authors. These shunts may be directedfrom the syrinx to the subarachnoid or pleural space or from the fourthventricle to the subarachnoid space. Ventriculoperitoneal (VP) orventricoloatrial (VA) shunts are recommended if hydrocephalus is present. Schlesinger (et al) [14] have reported good results with percutaneousaspiration of the hydromyelic cavity. Other authors report that aspiration isfollowed by rapid filling of the cavity from the ventricular system. [10,17]Based on the hydrodynamic hypothesis that the syrinx is a communicatinghydromyelia, these authors contend that a needle tract is not sufficientto maintain patency. [10,13] Recently Gardner (et al) [10,14] have advocated a procedure calledterminal ventriculostomy. The terminal ventricle is that portion of thecentral canal that extends below the conus medullaris into the filumterm
inale. [11] This technique involves a laminectomy over the caudal end of the syrinx, opening the filum and draining the syrinx. As thisprocedure does not decompress the malformation of the foramen magnum,improvement is likely to be seen in patients who are symptomatic only fromthe hydromyelia. [12,13] In a review of 127 cases of ACM I, Levy (et al) [10] found that 46 percentof patients improved during long-term follow up, while 25 percent deteriorated despite treatment. In reviewing the literature, they found that the natural history of this disease has not been established. Numerous reports ofprogressive deterioration following long periods of stability suggest theintermittent course of this disease. In view of these findings, evaluation ofthe most effective mode of therapy is particularly difficult. Most authors agree that the best results are obtained in cases treatedearly as patients beyond a certain stage of disability have little potentialfor a useful recovery. [2,12,13,14] Those patients having only AC
M I appearto have a better prognosis than those with both ACM I and hydromyelia.Improvement is often related to the arrest of progression rather thanrestoration of function already lost. The subjective improvement of pain,motor and sensory deficits represents a functional recovery for many individuals, however. [(S4.9)-----------------------------------------------------------------------] Nursing Management
******************************************************************************************************************************
challenge to the neuroscience nurse. Although treatment may arrest theprogression of symptoms in most individuals, seldom is there any objectiveimprovement. The deficits which have occurred prior to diagnosis are thereforelikely to be permanent. In concluding its seven-year study of chronic illness, the Commissionon Chronic Illness defined chronic disease as: "All impairments or deviationsfrom normal which have one or more of the following characteristics: arepermanent, leave residual disability, are caused by nonreversible pathologicalalteration, require special training of the patient for rehabilitation, or maybe expected to require a long period of supervision, observation, or care."[11] Nursing must regard Arnold-Chiari malformation as a chronic disease andfocus on those aspects of care which facilitate maximum adjustment to theillness utilizing all phases of the nursing process. [(S4.10)----------------------------------------------------------------------] Assessment The purposes of the neurological ass
essment are: 1) to determine thepresence of a life-threatening situation. 2) detect abnormal nervous systemfunction in order to determine alterations in daily living secondary to thedysfunction. 3) to detect changes in nervous system function in order tomonitor stability or the instability of nervous system disease, and 4) tolocate the type and extent of the healthy nervous system that can be usedfor rehabilitation. [7] The initial assessment of patients focuses on detecting the presence ofa life-threatening situation. Evaluation of the respiratory status and thefunction of the lower cranial nerves takes precedence. Patients with bulbardysfunction are prone to aspiration and respiratory embarrassment. For the child with a myelomeningocele, the spinal sac must be assessedfor size, condition of skin, leakage of fluid, and signs of infection. Ruptureof the sac may predispose the child to meningitis. Although hydrocephalusrarely develops until after closure of the spinal defect, an acute increase inintracranial p
ressure can occur from compression of the sac. Measurement ofhead circumference and evaluation of the fontanelles are therefore importantfor baseline and postoperative data. The motor system is assessed for strength, weakness, tone, atrophy,and the quality of gait. The sensory system is evaluated for numbness, dysesthesias, and the loss of pain and temperature sensations. Lossof sensation makes the patient particularly susceptible to injury. Headacheand pain in the cervical area are evaluated in terms of location, duration,intensity, and quality of the pain. Information about exacerbating factorsand methods of pain relief are obtained from the patient's verbal report. The cerebellar system is assessed for nystagmus, ataxia, dysmetria anddifficulties with coordination. Cerebellar dysfunction may jeopardize thepatient's ability to perform activities of daily living. Another important aspect of assessment is the patient and family'spsychosocial adjustment to the illness. The child with ACM-2 and an associatedmye
lomeningocele faces a lifetime of medical care, discomfort, and financialexpense. This places an extreme hardship on the patient and family. Feelingsof guilt, helplessness, and hostility are common. The adult patient withACM I may have similar feelings, especially if he/she has been misdiagnosed. Assessment of patient/family strengths and weaknesses is essential for the identification of coping strategies. It is also important to assess their knowledge of the disease process and impending surgery. [(S4.11)----------------------------------------------------------------------] Planning Information obtained from the baseline assessment of the patient withArnold-Chiari Malformation is utilized in the planning phase of the nursingprocess. Anticipation of patient/family needs preoperatively allows for morecomprehensive care post-operatively. An important aspect of planning is to set aside adequate time toprepare the patient and family for diagnostic procedures and surgicalintervention. This preparation includes pr
oviding needed informationabout the procedures and expected outcomes, answering questions and clarifying any misconceptions, preparing them for the residual deficits,and appraising the rehabilitation process.[1] A multidisciplinary approach to the patient with Arnold-Chiari malformationis imperative. Dietary services, physical therapy, occupational therapy, andsocial work services are essential components of the health care team.Patients with bulbar dysfunction have specific dietary needs which must bemet to insure adequate nutrition. Motor, sensory, and cerebellar deficitsrequire physical and occupational therapy to promote optimum adjustment to afunctional recovery. The emotional needs and financial concerns of thepatient/family are many. Appropriate referrals to community agencies andsupport services in the early course of the hospitalization help to relievemany of these burdens. [(S4.12)----------------------------------------------------------------------] Intervention Postoperative intervention again fo
cuses on assessment. Detecting changesin nervous system function in order to monitor the stability or instability ofnervous system disease is the primary focus. Following posterior fossa surgery, respiratory status and cranial nervefunction are the major concern. Because of the proximity of the cranial nervenuclei to the respiratory center, intubation may be required for a longerperiod of time. Postoperative edema may exacerbate any pre-existing deficits.Protection of the airway and prevention of aspiration are imperative. Theintegrity must be monitored and external feedings delayed until aspiration isno longer a danger. Because of the proximity of the nauseas center, theprophylactic use of antiemetrics helps prevent aspiration of vomitus. The posterior fossa decompression of Arnold-Chiari malformation oftennecessitates a lose closure of the dura. Cerebrospinal fluid leaks aretherefore a potential hazard which may predispose the patient to meningitis. If a shunt is placed for hydrocephalus, flat bedrest is ma
intained forseveral days to prevent rapid decompression of the ventricles.Ventriculoperitoneal shunts carry the risk of paralytic ileus. Assessmentof bowl sounds prior to the advancement of diet is important. Pain relief is provided for by the use of mild analgesics. Strong narcoticsare contraindicated because of the suppression of the respiratory center andthe clouding of the sensorium. The motor, sensory and cerebellar systems are assessed for changes infunctional ability. Rehabilitation services are begun as soon as the patientcan be mobilized. If sensation is impaired, the skin must be protected frominjury and the patient counseled on the proper skin care. Involving the family in the patient's rehabilitation program is important.Not only does this increase the continuity of care, it contributes to thefamily's well being by allowing them to be useful participants. This plannedfamily involvement also serves to educate them in the anticipation of thepatient's future needs. [(S4.13)---------------------------
-------------------------------------------] Evaluation The evaluation phase of the nursing process reviews the phases ofassessment, planning, and intervention. How well have the patient/familyadjusted to the disease process? What effect has surgical intervention hadon the course of the illness? What further need for rehabilitative servicesare there? have the patient and family received adequate financialassistance and emotional support? What effect do the residual deficits haveon the patient's ability to perform activities of daily living? The answers to these questions provide not only information for evaluation but alsovaluable assessment data for the continuation of the process. Through theuse of the nursing process, the nurse is able to systematically address theseissues and facilitate maximum adjustment to this chronic illness. [(S4.14)----------------------------------------------------------------------] Summary Arnold-Chiari malformation is a condition of the cervico-medullary junctionwhich is charac
terized by caudal displacement of the cerebellum, brainstem,and the fourth ventricle. Through the use of the nursing process, the nurseis able to facilitate maximum adjustment to this chronic illness.
**************************************************************************************************************************************
ARNOLD-CHIARI MALFORMATIONS (ACM) # Etiology: Both Chiari type l and ll may be due to a malformed posterior fossa. # Pathogenesis: There many theories related to the causes of Arnold Chiari type ll including pulling of the brainstem and lower cerebellum into the foramen magnum by anchoring of the spinal cord by the meningomyelocoele. None really explains all the malformations. Chiari l may be due to a small posterior fossa. # Epidemiology: Both Arnold Chiari l and ll are sporatic although type l can be inherited. # General Gross Description: Arnold Chiari type ll is almost always associated with a meningo- myelocoele. Consists of malformation of the brainstem and cerebellum leading to extension of the medulla and cerebellum through the foramen magnum where the cervical spinal cord should rest. Usually associated with hydrocephalus. Arnold Chiari type l is not related to spina bifida, is often seen in adults and consists of herniation of the cerebellar tonsils through the foramen magnum around the cervical spi
nal cord. # General Microscopic Description: Arnold Chiari ll shows variable malformations and repositioning of nuclei in the brainstem with disorganization and atrophy of the herniated cerebellum. Arnold Chiari l shows some loss of neurons and gliosis of the herniated cerebellar tonsils. # Clinical Correlations: Chiari ll is almost always seen with meningomyelocoele and hydrocephalus with all their clinical problems. It may cause brainstem or cervical cord compression. Seen in children and adults. Chiari l is sporatic or occasionally inherited. It can cause headaches, brainstem compression and rarely sudden death. Usually becomes manifest during middle life.
*****************************************************************************************************************************************
What is Arnold-Chiari Malformation? "The Chiari Malformations are a group of defects of posterior fossa anatomy" (a type of defect to the back of the brain stem where it grow in a tapered fashion,growing down the center of the spinal cord)", ranging from minor displacement of cerebellar tissue to gross bony defects or cerebellar hypoplasia. While some of these disorders are obvious at birth, others may present to a clinician late in life, with complaints ranging from headaches and sensory changes to vertigo, imbalance and hearing loss. Patients may have symptoms mimicking a cellebellopontine angle mass." What are some of the symptoms associated with Arnold-Chiari? Blurred vision Burning and or shooting pains in head and neck Can't locate hand/feet position without looking Decreased sensation in arms Decreased sensation in feet Decreased sensation in hands Decreased sensation in mouth Decreased sensation in throat Difficulty adjusting vision to changes in light Difficulty doing fine movements - pickin
g up coins, etc. Difficulty focusing vision on printed materials Difficulty tracking moving objects Difficulty walking down stairs - can't tell where the bottom step is Difficulty walking on uneven surfaces Dizziness - vertigo *blackout* feeling when standing up or changing position Double vision Dropping things easily Electric shock-like pain down spine Feeling a pull to one side while standing Feeling of pressure behind eyes Foot drop Frozen Shoulder (numbness/pain/tingling) General loss of balance Gagging in sleep or while lying down Head pain when getting up or changing position Headache - frequent Headache when coughing or sneezing - sudden Heaviness on chest (pressure) when lying flat Intense burning in extremities Loss of bladder sensations Loss of gag reflex Loss of sense of smell Loss of feeling on skin surface Loss of sexual interest/sensation Loss of taste Muscle spasm/increased muscle tome in hands Neck - hard to move - restricted movement Neck pain or Neck spasms Not feel
ing the ground under your feet Pain along eye, jaw and ear - same side Pressure in neck Ringing in ears Shallow breathing/sleep apnea at night Swallowing Problems Swaying back and forth while sitting or standing Tripping while walking Tremor/trembling in hands Whooshing/fluid sound in ears How can I tell if I have Arnold-Chiari? The only way that you can be accurately diagnosed with Arnold-Chiari is through the use of an MRI (Magnetic Resonance Imaging) hydrocephalus
hypo/agenesis of corpus callosum, colpocephally
luckenschadel skull

Chiari III
further herniation
4th ventricle below foramen magnum
encephalocele or myelomeningocele

associated with:
syrinx

**definately problesm with breathing/ some sleep disorders. I'm not a doctor. I also am just simply being diagnosed with the same thing, and am tryin to obtain as much info as possible myself. hope this helps. I have more.

Follow Ups:


  • IMPORTANT : Information not intended as medical advice. If you suspect that you have a sleep disorder you should seek care from a qualified professional. Read Terms of Use.
  • The Sleep Forums are not to be used for commercial purposes.
  • Commercial products and services are not endorsed by Sleepnet.com.
  • Sleep Deprivation due to Sleep Apnea and insufficient sleep are common and can present as insomnia, narcolepsy, or idiopathic hypersomnia. In infants and children sleep problems commonly present themselves as ADD or ADHD.


Copyright ©1995-2006 Sleepnet.com., All rights reserved